Parks, Huw CW;
(2024)
Spatiotemporal X-ray Techniques for the
Quantification of Lithium-Ion Battery Degradation.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
Battery technology is becoming increasingly crucial in achieving global targets for electrified transportation and the deployment of renewable energy, therefore, the demand for batteries with high energy density and extended lifespan is continuously growing. One promising solution is high nickel containing layered cathodes, with NMC811 (Li1[Ni1-x-yMnxCoy]O2, x=0.1 and y=0.1) presenting as the premier candidate for ubiquitous adoption of electric vehicles. This cathode chemistry has the potential to significantly enhance the energy density of next-generation lithium-ion batteries. Nevertheless, NMC811 faces a notable challenge; they can experience a substantial decrease in capacity during cycling, particularly when subjected to high-voltage and high-temperature conditions. Cracking in secondary particles has been suggested to cause reduced performance due to insufficient connection between particles and the conductive architecture in the electrode matrix, as well as fresh surface exposure to electrolyte and subsequent oxygen release accompanied by electrolyte oxidation. Establishing the nature of crack generation, formation, and propagation is paramount to understanding the degradation modes that govern decline in battery performance. Cracking has several possible origins; however, it can be classified in two general cases: mechanically induced, during manufacturing, or electrochemically induced, during operation. This thesis looks to design novel spatial resolved in situ techniques using X-ray imaging and diffraction that will help us understand the true nature of cracks development and suggest possible mitigation solutions to reduce cracking detrimental to the battery’s performance. Cracking is intrinsically linked to the crystal structures underpinning the whole battery’s operation and these layered crystals have complex volumetric expansion properties as a function of lithium content. Thus, NMC crystallographic expansion properties in both polycrystalline and single crystal morphologies are also presented here. Thought to have extended life cycle due to their resistance to cracking, the single crystal materials diffraction is measured in operando to further grasp the volumetric behaviour that may be at the heart of cracking phenomena
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Spatiotemporal X-ray Techniques for the Quantification of Lithium-Ion Battery Degradation |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2024. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Chemical Engineering |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10200857 |
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